Federal officials investigating the deadly West Texas collision between at Union Pacific train and a tractor-trailer hauling a wind turbine base are trying to determine why the tractor-trailer was stopped on the tracks.

Around 5 p.m., a train derailed near Oak Street and Dot Stafford Street, the city said in a statement. Later that evening, authorities confirmed the derailment was caused by the train colliding with a commercial tractor-trailer on the railroad tracks.